EP2741587B1 - Device for varying the intensity of the light in luminous charges - Google Patents

Description

The present invention relates to a light dimming device, and more particularly the possibility for such devices to adapt to all currently available lamp technologies on the market, of course when they are dimmable, and to allow a "clean" operation. Of these lamps, both when they are lit and when they are extinguished. It also relates to a method of operating such a device.

In a very general way, the drive devices are intended to turn on or off lamps at a variable luminance level, but also to adjust their brightness level in real time using a controller. This adjustment is conventionally performed by phase cutting, the lamp then being a light load controlled by a power stage is in angle cut mode, for example for filament lamp type of luminaires, or in conduction mode at the same time. angle especially for inductive luminous loads such as ferromagnetic transformers for 12- or 24-volt halogen lamps. This type of dimming device concerns conventional, incandescent or halogen lamps, as well as more recent sources such as compact fluorescent lamps (CFL) or light-emitting diodes (LEDs). Relatively newcomers to the sphere of light sources, these lamps CFLs and LEDs also have a brightness level that is adjustable, preferably in angle cut mode.

The variable supply of charges is thus carried out in practice by means of an output signal cut in the phase according to a switching mode which depends on the nature of the load. This "cutting" operation has the disadvantage of generating noise or spurious signals on the sector, inducing electromagnetic compatibility (EMC) of the drive which is not satisfactory, because electromagnetic disturbances that are not tolerable occur. for the equipment that is in its environment.

In order to reduce these parasitic signals substantially, it is customary to integrate a filter capacitor connected to the converter between the phase and the output to the load, which then makes it possible to filter out these parasitic signals. The more the lamp to be controlled is of high power (greater than 300W), the more the presence of this type of capacitor is necessary, and its filtering is effective.

With charges of the CFL and LED type, which are small powers (less than 10W), this capacitor has no significant effect on a lit lamp, and the user does not see any visual and / or sound effect. However, when the lamp is off, it is no longer controlled by phase cutting, and the presence of the filter capacitor causes permanent circulation of a leakage current passing through the lamp.

This leakage current can cause visual and / or audible effects on light loads, and this is particularly the case with CFL and low power LEDs. In this case, the lamp can emit a noise that is perfectly audible to the user, and also produce flashes of light, or even a low and continuous lighting perfectly visible to the user. These sound and visual phenomena, unwanted and uncontrolled correspond therefore to nuisances for the user. They are obviously not desirable and must be removed.

• des lampes à halogène ou à incandescence de forte puissance (supérieure à 300W) nécessitant un condensateur de filtrage qui génère un courant de fuite de plusieurs mA dans les lampes ;
• des lampes CFL ou LED de petite puissance (inférieure à 10W) sensibles au courant de fuite lorsqu'elles sont éteintes.

The problem that arises, at present, is to be able to control, with a phase-switching dimmer, loads as varied as:

• high-power halogen or incandescent lamps (greater than 300W) requiring a filter capacitor that generates a leakage current of several mA in the lamps;
• CFL or LED lamps of low power (less than 10W) sensitive to the leakage current when they are extinguished.

The present invention proposes to respond to this problem with a dimming device ensuring the electromagnetic compatibility and guaranteeing a "clean" operation of the lamps regardless of the type of load.

• une unité de contrôle de type microcontrôleur commandant un étage de puissance de découpage de phase connecté entre la phase du secteur et au moins une charge lumineuse ;
• une alimentation à découpage raccordée entre phase et neutre du secteur ;
• un condensateur de filtrage connecté entre la phase du secteur et la charge, en parallèle de l'étage de puissance de découpage, pour réduire les bruits sur le secteur.

For this purpose, the dimmer device of the intensity of the light of the invention conventionally comprises:

• a microcontroller-type control unit controlling a phase-switching power stage connected between the mains phase and at least one light load;
• a switching power supply connected between phase and neutral sector;
• a filter capacitor connected between the mains phase and the load, in parallel with the chopper power stage, to reduce noise on the mains.

According to the invention, this device is essentially characterized in that it comprises means for suppressing the leakage current generated by the filter capacitor when the load is not controlled. It is therefore not a question of diverting this leakage current, or of diminishing its intensity, but of cutting it.

More precisely, these means for suppressing the leakage current consist of means for disconnecting the capacitor for filtering the load when it is not controlled. The idea underlying the invention is therefore to connect the filter capacitor when the lamp is on, and disconnect when the lamp is off so as to cut the leakage current and thus prevent it from reaching load.

In concrete terms, said means for disconnecting the filtering capacitor consist of an electromechanical relay whose contact is placed in series with the filter capacitor. Therefore, the filter capacitor and electromechanical relay assembly is connected between the mains phase and the load, in parallel with the chopper power stage.

This electromechanical relay is controlled by the control unit.

The relay contact is closed when the load is controlled, and the relay contact is open when the load is not controlled.

• détection d'une alimentation de la charge par le variateur ;
• fermeture du contact du relais ;
• temporisation ;
• activation du découpage de phase jusqu'à obtenir le niveau de luminosité désiré ;
• détection d'une cessation de l'alimentation de la charge par le variateur ;
• désactivation du découpage de phase ;
• ouverture du contact du relais.

Modifications in the control of the dimming device of the intensity of the light to which load control instructions are applied, in particular for "clean" operation of various light loads as described above, are managed through an operating method which, according to the invention, is expressed by the following steps:

• detection of a load supply by the drive;
• closing the relay contact;
• time delay;
• activation of the phase division until the desired brightness level is achieved;
• detection of a cessation of the supply of the load by the drive;
• deactivation of the phase division;
• opening the relay contact.

Thus, when the lamp is off, the relay contact is open.

When the drive turns on the lamp, the control circuit closes the relay contact to connect the filter capacitor, and then starts and varies the phase switching to obtain the desired brightness level.

Finally, when the drive switches off the lamp, the control circuit stops the phase cutting to obtain a zero brightness level, then opens the contact of the relay to disconnect the filter capacitor and thus ensure the absence of leakage current in the lamp.

Unwanted acoustic and light phenomena are thereby eliminated.

Preferably, the closing of the contact of the relay is synchronized with a detection of the zero crossing of the mains voltage. This possibility makes it possible to avoid circulating a current that is too strong in the relay when closing the contact and thus guaranteeing its good operation over time. Indeed, if the relay is closed to the zero of the mains voltage, this current is zero. If the relay is closed out of synchronism with the zero of the mains voltage, this current can be very important and accelerate the aging of the relay.

According to one possible configuration, the delay between the closing of the contact of the relay and the activation of the phase cutting is of the order of 20 ms. This is a time short enough not to be detected by a user's eye. This means that the latter will have the impression that the lighting of the lamp is immediate following the manipulation of eg the controller of the drive.

• la figure 1 est un schéma électronique d'un dispositif variateur de l'intensité de la lumière dans des charges lumineuses selon l'invention ;
• la figure 2 montre un organigramme illustrant le procédé de fonctionnement d'un tel dispositif.

The invention will now be described in more detail with reference to the figures for which:

• the figure 1 is an electronic diagram of a dimmer device of the intensity of light in light loads according to the invention;
• the figure 2 shows a flowchart illustrating the method of operation of such a device.

With reference to the figure 1 , the drive device of the invention mainly comprises a power stage (1) phase cutting, a microcontroller type control unit (2) and a switching power supply (3).

The power stage (1) is conventionally based on two power MOSFET transistors, arranged head-to-toe between the phase and the load, and whose switching allows the power supply in angle cut mode or conduction mode. angle of charge (4) connected at the output of this power stage (1).

The device of the invention is a "three-wire" type inverter, that is to say that it is connected to the neutral of the network, to the phase of the network, and to the light load. Such a device is therefore powered between the phase and the neutral of the network. Thus, the switching power supply (3) is connected between the phase and the neutral of the network.

It is the microcontroller (2) that carries out the various logical processes necessary for the automated operation of the assembly, primarily controlling the MOSFET transistors by providing instructions according to the mode of cutting.

In parallel with the power stage (1) is connected a filter capacitor (5), between the phase of the network and the load, the role of which consists in filtering the spurious signals emitted during the cutting operations. The filtering capacitor (5) is selected from a wide selection according to the desired filtering level.

An electromechanical relay (6) is placed in series with this filter capacitor, the contact (7) of the relay (6) for disconnecting or connecting the filter capacitor (5) to the load. The contact (7) of the relay (6) is controlled by the microcontroller (2) via a link (8) at the output of the microcontroller (2). The microcontroller (2) controls the closing of the contact (7) when the lamp (4) is on, and controls the opening of the contact (7) when the lamp (4) is off.

This drive device comprises a detection stage of the zero crossing of the mains voltage (not shown), and which conventionally consists of an optocoupler whose output is connected to the microcontroller (2), the signal at the output of the optocoupler reflecting the signal. phase and allowing the microcontroller (2) to detect the zero crossing of said phase.

As shown in the organization chart of the figure 2 , which corresponds to the operation of the method of the invention, the contact (7) of the relay (6) is open when the lamp (4) is off, and this is the starting point of the flowchart.

As long as the lamp (4) is off, the relay (6) is controlled in the OFF position.

When the drive turns on the lamp (4) following a command given by the user, the microcontroller (2) starts to monitor the phase signal, and controls the closing of the contact (7) of the relay (6) when It detects the zero crossing of the mains voltage. The connection of the capacitor (5) is thus synchronized with the zero crossing of the mains voltage.

Following a delay of about 20 ms after the closing of the contact (7) of the relay (6), the microcontroller (2) controls the activation of the phase cutting to obtain the desired brightness level of the lamp (4) .

As long as the lamp (4) is on, the relay (6) is controlled in the ON position.

When the dimmer switches off the lamp (4) following a command given by the user, the microcontroller (2) controls the deactivation of the phase division in order to obtain a level of zero brightness, then commands the opening of the contact (7). ) of the relay (6) to cut the leakage current generated by the capacitor (5) and thus ensure the absence of leakage current in the lamp (4). The opening of the contact (7) of the relay (6) in fact disconnects the capacitor (5) filtering the lamp (4), at least until the next ignition of the latter.

The invention has been described by means of a preferred solution, which is however not limiting of the invention. This includes variants, in particular in terms of the action time, and means for connection / disconnection of the capacitor when the lamp is off, which can take other forms, such as for example a bi-directional opto-transistor of the MOSFET type which would replace the relay.

Claims (7)

1. Dimmer device for varying the intensity of the light in lighting loads (4) that can be of dimmable compact florescent (CFL) or dimmable light-emitting diodes (LED) type, comprising:

   - a control unit (2) of microcontroller type controlling a phase switching power stage (1) connected between the phase of mains and at least one lighting load (4);

   - a switched-mode power supply (3) connected between the phase and the neutral of the mains;

   - a filtering capacitor (5) connected between the phase of mains and the load, in parallel with the switching power stage (1), to reduce the noises on the mains;

   characterized in that it comprises means for eliminating the leakage current generated by the filtering capacitor (5) when the load (4) is not controlled, said leakage current elimination means consisting of means for disconnecting the filtering capacitor (5) from the load (4) when it is not controlled.
2. Dimmer device for varying the intensity of the light in lighting loads according to the preceding claim, characterized in that said means for disconnecting the filtering capacitor (5) consist of an electromechanical relay (6) whose contact (7) is placed in series with the filtering capacitor (5).
3. Dimmer device for varying the intensity of the light in lighting loads according to the preceding claim, characterized in that the electromechanical relay (6) is controlled by the control unit (2).
4. Dimmer device for varying the intensity of the light in lighting loads according to the preceding claim, characterized in that the contact (7) of the relay (6) is closed when the load (4) is controlled, and the contact (7) of the relay (6) is open when the load (4) is not controlled.
5. Method for operating a dimmer device for varying the intensity of the light in lighting loads according to the preceding claims, characterized by the following steps:

   - detection of a power supply of the load (4) by the dimmer;

   - closure of the contact (7) of the relay (6) in series with the filter capacitor (5), the contact (7) and the filtering capacitor (5) being electrically in parallel with the dimmer;

   - time delay;

   - activation of the phase switching until the desired brightness level is obtained;

   - detection of a cessation of power supply powering of the load (4) by the dimmer;

   - disactivation of the phase switching;

   - opening of the contact (7) of the relay (6).
6. Method for operating a dimmer device for varying the intensity of the light in lighting loads according to the preceding claim, characterized in that the closure of the contact (7) of the relay (6) is synchronized on a detection of the zero crossing of the mains voltage.
7. Method for operating a dimmer device for varying the intensity of the light in lighting loads according to the preceding claim, characterized in that said time delay is of the order of 20 ms.

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